The Irish Government is facing widespread demands to respond to claims of an effective amnesty for IRA killers operating in the republic for more than a decade.
Politicians, victims' campaigners and the family of the only prison officer assassinated south of the border during the Troubles have all urged an immediate response over the revelations by a former justice minister.
Jeffrey Donaldson, a senior MP in the Democratic Unionist Party, said he is appalled by the development which he warned will have a significant impact on ongoing talks about dealing with the past.
The Lagan Valley MP said suggestions by Dublin's ex-justice minister and former Tanaiste Michael McDowell that a de facto amnesty has operated south of the border for years raises serious questions about investigations into several killings.
"Frankly, I am not surprised by this revelation but I am appalled by it," said Mr Donaldson, his party's victims spokesman.
"The innocent victims of terrorism in the Irish Republic are entitled to justice and it is a matter of concern that the Irish Government appears to have taken a unilateral decision not to pursue justice in such cases."
Mr McDowell last week told the Press Association of "a consensus" in the Republic dating back at least 14 years ago that the Garda would no longer be prosecuting historical cases.
He said: "In fact what happened in the Republic was that there was just a decision by the guards to use their resources to prevent current crime and current offences and not to go back over the IRA's campaign of violence."
Mr Donaldson said Taoiseach Enda Kenny must immediately clarify the Irish government's current policy on prosecuting past IRA and loyalist paramilitary crimes.
"It will have a major bearing on the ongoing discussions that we are having in Northern Ireland about how we deal with the legacy of the past," he said.
"I think we need to know from the current Irish government: is the position outlined by Michael McDowell the current position of the Irish government in relation to historic cases?"
Margaret Urwin of Justice for the Forgotten, which has campaigned for decades for the truth behind the 1974 Dublin and Monaghan bombings, said the remarks suggest they had been misled.
"We had always been told that if any new evidence emerged it would be vigorously pursued," she said.
"I find this astonishing."
Ms Urwin said the revelation raises concerns about whether all available evidence was handed over to the Barron Inquiry, an Irish government-ordered investigation into the atrocity which killed 34 people, which ran between 2000 and 2003.
"If there was anything that was incriminating that could have given rise to prosecutions, was it withheld or suppressed?" she asked.
Austin Stack, whose prison officer father Brian died after being shot by the IRA in Dublin in 1983, said Mr McDowell's remarks suggest his family were "led up the garden path" by the State.
"I think it is absolutely disgraceful," he said.
"Who exactly was involved in this consensus and why weren't the victims consulted?
"I am asking (justice) Minister Frances Fitzgerald to come out and categorically state if there is an amnesty or not."
Mr Stack said his family has repeatedly been reassured that the investigation into their father's murder remained open.
But he added a de facto amnesty could explain why the case was "put on the back burner".
An advocate of restorative justice, Mr Stack said an amnesty should only be granted if the perpetrators spoke to the families of the victims and faced up to their actions.
"It can't be just a blanket amnesty without extracting anything in return," he said.
The revelations would impact on the cases of several servants of the State who died defending their country, he added.
During talks in 2000, Mr McDowell - then attorney general - suggested to his British counterpart that fugitive IRA suspects could be granted royal pardons.
The contentious measure was proposed as both governments were trying to bring senior republicans "in from the cold" during a critical stage in the fledgling peace process, he revealed.
Asked if there were similar proposals discussed in the Irish Republic, he said: "Generally speaking there was a consensus in the Republic that the police would no longer be prosecuting historical cases."
Debate is raging in Northern Ireland about how to deal with past murders linked to the recent conflict.
Last year, the North's attorney general John Larkin created a furore when he suggested no further investigations should be carried out into murders committed before the Good Friday Agreement.
A British government-ordered inquiry into so-called 'comfort letters' issued to IRA fugitives found last week that they were lawful and not an amnesty.
The letters advised the republican suspects they were not wanted by police and only publicly emerged when the trial collapsed of a man suspected of the 1982 IRA Hyde Park bombing.
The nationalist Social Democratic and Labour Party (SDLP) also urged the Irish Government to clarify any decisions taken about prosecuting paramilitary fugitives.
Stormont MLA Alban Maginness, the party's justice spokesman, said: "Transparency in all things relating to on-the-runs is something that the SDLP would want to see.
"It would be in the public interest if the Irish Government were to make any methodology they used in relation to this issue public."